British television naturalist David Attenborough joined Instagram on Thursday at the age of 94, quickly racking up more than one million followers in his first few hours.

The speed at which Attenborough attracted his first million followers was a new record for the platform, according to Guinness World Records. It took him just four hours and 44 minutes; the previous record holder, Jennifer Aniston, managed the feat in five hours and 16 minutes.

The veteran broadcaster, who has enjoyed a stellar 60-year career chronicling the natural world for audiences, used his inaugural post on the photo- and video-sharing platform to warn "saving our planet is now a communications challenge".

"I am making this move and exploring this new way of communication to me because, as we all know, the world is in trouble," he said in a one-minute 12-second video message that attracted nearly 20,000 comments within six hours.

"Continents are on fire. Glaciers are melting. Coral reefs are dying. Fish are disappearing from our oceans. The list goes on and on," he added.

Attenborough joined the US social media site, which is owned by Facebook, ahead of the release of his latest film, "A Life On Our Planet", on Netflix from October 4.

The Instagram account will be managed by the documentary's makers and host further video messages from Attenborough in the coming weeks, they said in a message posted on the site.

"Join me, or as we used to say in those early days of radio, stay tuned," he added as he concluded his first and so far only post.

Earlier this month, he gave his starkest warning yet on the need for humanity to safeguard species from mass extinction for the sake of humankind's own survival in a one-hour film, "Extinction: The Facts".

It aired on the BBC in Britain in the same week as international experts warned in a report that global animal, bird and fish populations have plummeted by more than two-thirds in less than 50 years due to humans' rampant over-consumption.